This invention relates to a checkvalve for dispersing a fluid into a flowing stream. More particularly this invention relates to a checkvalve useful in dispersing agricultural chemicals into a stream of irrigation water.
In recent years a method for adding agricultural chemicals to farmland has developed. This method commonly known as xe2x80x9cchemigationxe2x80x9d involves the introduction of the agricultural chemicals into irrigation water with subsequent dispersion of the irrigation water containing the chemicals onto the cropland. Chemicals such as fertilizers, insecticide, herbicides, etc. can dispersed by this method. In order to be effective, the chemical must be well dispersed in the irrigation water prior to the water being sprayed upon the cropland. Care must be taken in order to assure that in the event of a shutdown in the flow of irrigation water the chemical will not flow into the water source causing contamination of the source of water. Also, it is necessary that irrigation water does not flow into the chemical supply system causing overflow and area contamination.
Although some agricultural chemicals are soluble in water, it is also desirable to effectively disperse chemicals which are not readily soluble or are insoluble in water. These chemicals are often supplied dissolved in a water insoluble solvent such as kerosene. Certain chemicals such as fertilizers can also be available as a slurry of solids in a liquid. Therefore, it is desirable to effectively disperse a water insoluble (or minimally soluble) material into a stream of irrigation water.
A number of valve systems have been suggested the prior art. Savage in U.S. Pat No. 3,267,959 (1966) discloses a valve which is said to function as an anti-fouling and anti-siphoning valve in irrigation system. The valve is provided with a neck portion which designed to extend into the liquid stream being treated so that the chemicals being discharged will be xe2x80x9cimmediately absorbed by the liquid and removed from the position of the valve properxe2x80x9d. The valve is designed to open when the chemical being injected is subjected to pressure equal to or greater than the sum of the pressure of the fluid flowing in the pipe into which the valve extends. An array of slots is provided in the tip portion so that when the chemical flows past the O-ring seal, the chemical can disperse through the slots thereby providing an early release of discharge pressure to avoid dislodging the O-ring seal. This valve has a significant disadvantage in that, when the flow rate of the chemical is increased and the valve member containing the O-ring travels past the end of the housing containing the slots, the valve stem can be subjected to a significant lateral force as the result of the flow of the liquid stream past the valve. This lateral force can bend the valve stem resulting in failure of the O-ring valve to seat properly. Deflection of the extended valve stem can also result in the valve jammping open. Either effect will allow the chemical to continue to leak into the system, or allow liquid in the conduit to pass through the check-valve back to the source of the chemical.
Gilroy in U.S. Pat No. 4,437,611 (1984) discloses a spray nozzle to be used in a sprinkler system in a corrosive or dirty environment. The spray nozzle is designed to be mounted in a conduit wall essentially flush with the inside of the conduit into which a spry of liquid is to be provided. This nozzle has a disadvantage that the moving parts are continually bathed in the chemical being injected. Since many of the chemicals used in agriculture are corrosive, special materials must be used to avoid corrosion and plugging of the valve. Additionally, introduction of the chemical along the conduit wall does not provide for optimum dispersion of the chemical into the flowing stream.
In a series of three patents, Stamps et al., disclose a method and apparatus for dispersing substantially water soluble agricultural chemicals into an irrigation system. This method involves dispersing the chemical by passing a pressurized stream containing the chemical through an orifice. The dispersed stream passes through a checkvalve and subsequently through an entry line, which projects into the water stream. This procedure has the disadvantage of requiring a substantial amount of additional equipment in order to effectively disperse the chemical into a stream which must then be dispersed into the main irrigation stream. U.S. Pat. Nos. 3,464,626 (1969), 3,326,232 (1967), and 3,375,976 (1968).
None of these references disclose a device capable of effectively dispersing a fluid at a variety of flow rates into a moving stream of liquid. All of these referenced devices and methods have the disadvantages disclosed hereinabove. Accordingly, there is a need for an apparatus which can effectively disperse a fluid into a stream of a liquid while also serving as a checkvalve to avoid unintentional flow of the fluid into the liquid or the liquid back into the source of the fluid.
It has been found that the above described disadvantages can be overcome with the checkvalve of the instant invention. The instant fluid dispersing checkvalve comprises a conduit having a passage extending longitudinally therethrough. The passage has an inlet end and an outlet end, and an orifice is located at the outlet end of the passage. A slotted housing which has a first end is attached to the outlet end of the conduit. A valve seat circumscribes the orifice. A valve which is adapted to reside in said valve seat is slidably located in the housing. A valve retainer, is also slidably mounted in the housing to urge the valve into contact with the valve sea. A spring means is located in the housing and is operatively connected to the valve retainer to yieldingly urge the retainer into contact with the valve to provide a seal when the valve resides in the valve sea. The spring means is held in place in the housing by a spring retainer which is fixed to the second end of the housing and engages the spring means.
In another embodiment, the instant invention comprises a method for dispersing a fluid into a liquid stream. The fluid flows through a passage in a conduit and exits through an orifice. The exiting fluid displaces a valve from a valve seat which surrounds the orifice. The valve is urged against a valve retainer moving the valve retainer and valve longitudinally in a slotted housing away from the orifice. The valve retainer, is moved in opposition to a spring means compressing the spring means. The exiting fluid flows past the valve and is dispersed through slots in the slotted housing into the liquid stream. Upon termination of the flow of fluid, the compressed spring means acts to return the valve retainer and valve to provide contact between the valve and the valve seat and seal the orifice.